1. Field of the Invention
This invention relates to a valve insertion method without stopping passage of fluid, and a cutting tool.
2. Description of the Prior Art
A valve insertion method comprising drilling a hole in an already-installed pipe (or existing pipe) in a non-water-flow-stopping state, and inserting a valve in the hole thus cut in the already-installed pipe in a line including the same pipe has heretofore been known.
FIGS. 15(a) and 15(b) shows an outline of a conventional valve insertion method disclosed in U.S. Pat. No. 4,516,598.
According to the conventional techniques shown in these drawings, an already-installed pipe 1 is enclosed with a sealing case 800. The sealing case 800 houses a hole saw 802 and a gate 804 therein in advance. A circular opening is then drilled in the already-installed pipe 1 with the hole saw 802. After the opening is drilled, the sealing case 800 is turned as shown by arrows 850 in FIG. 15 (a), and the gate 804 is thereafter inserted into the circular opening 803 shown in FIG. 15(b).
The conventional techniques of FIGS. 15(a), (b) enable the insertion of the valve after the completion of the pipe cut-off operation to be carried out speedily. However, in the conventional techniques of FIGS. 15(a), (b), the dimensions of the sealing case 800 increase because it is necessary that the hole saw 802 having the dimensions of which are equal to those of the gate 804 to be inserted is housed in the sealing case 800.
FIG. 16 shows an outline of a conventional valve insertion method disclosed in U.S. Pat. No. 5,611,365 and International Patent Laid-Open WO97/31207.
In the method shown in this drawing, an already-installed pipe 1 is enclosed with a sealing case 600 first. A gate 601 is then turned with the sealing case 600 to cut-off the already-installed pipe 1 with a cutting tool 602 fixed to a free end of the gate 601. According to the conventional method described above, the dimensions of the sealing case 600 decrease because the cutting tool 602 has small dimensions. However, since the cutting tool 602 is fixed to the gate 601, the leakage of water is not perfectly prevented. The already-installed pipe 1 is cut-off with a tip type cutting tool 602. Therefore, in order to cut into an already-installed pipe 1 comprising a cast iron pipe or a steel pipe, the sealing case 600 has to be turned many times, so that it takes much time to cut-off the pipe.
U.S. Pat. No. 5,732,728 discloses a valve insertion method using an assembly provided with a rotary valve casing, a cutting assembly and a gate assembly. According to the conventional techniques, the gate assembly is fixed in place of the cutting assembly after a grooving operation is carried out, so that the dimensions of an apparatus decrease. However, in this prior art method, it is necessary to carry out an operation for replacing the cutting assembly with the gate assembly by opening and closing a seal means, so that the operations take much time.
Therefore, a primary object of the present invention is to provide a valve insertion method capable of carrying out valve insertion work speedily and miniaturizing a sealing case.
Another object of the present invention is to provide a cutting tool capable of improving a discharge rate of cutting chips producing in an operation for cutting an already-installed pipe (or existing pipe) in the valve insertion method.
One Aspect
In one aspect of embodiment of the valve insertion method according to the present invention, a valve assembly is inserted in an already-installed line by using a milling type cutting tool, the valve assembly and an operation valve so as to achieve these objects.
A worker prepares in advance the cutting tool, the valve assembly and the operation valve.
The cutting tool is supported so that it can be rotated freely around an axis set in an axial direction of the already-installed pipe, and it has cutting edges on its free end surface and outer circumferential surface.
The valve assembly has a valve casing forming a flow passage, a gate housed in the valve casing, and a valve spindle adapted to slide the gate in a direction which crosses the fluid passage at substantially right angles thereto.
The valve casing is provided with a first and second divisional cases separated from each other in the circumferential direction of the already-installed pipe.
Either one of these divisional cases is provided with a tool entering hole opened toward the center of the already-installed pipe.
The second divisional case is provided with a gate housing hole adapted to house the gate therein when the valve is opened, and enable the gate to move slidingly.
The gate housing hole and tool entering hole are provided in positions spaced from each other in the axial direction of the pipe.
The operation valve is fixed to the valve casing so that it can open and close the tool entering hole.
This valve insertion method has an assembling step, a drilling step, a grooving step, a tool takeout step and a transfer step which will be described below.
In the assembling step, a part of the already-installed pipe is enclosed air-tightly with the valve casing, and the gate and the cutting tool, which is independent of the gate, are housed in the valve casing with the gate and the cutting tool fixed thereto.
In the drilling step, the cutting tool is fed in the radial direction of the already-installed pipe as it is made to take cutting motions. The xe2x80x9ccutting motionsxe2x80x9d referred to above means motions for cutting the already-installed pipe with the cutting tool rotated around the set axis mentioned above.
In the grooving step, the valve casing is turned in the circumferential direction of the already-installed pipe with the cutting motions kept being made. Owing to the turning of the valve casing in this step, the cutting tool is turned in the circumferential direction of the already-installed pipe, whereby the cutting tool is made to take feeding motions. Consequently, the already-installed pipe is cut in the whole of a circumferentially extending portion thereof with the cutting tool without producing a cut-off section. Thus, a cut groove is formed (cut) in the portion of the already-installed pipe, and extends in the direction of the range of the whole circumference thereof.
In the tool takeout step, the cutting tool is taken out from the valve casing via the operation valve after the completion of the grooving operation. Thereafter the operation valve is closed.
In the transfer step, the valve casing is transferred in the axial direction of the already-installed pipe after the completion of the grooving operation, whereby the gate is transferred to a position corresponding to that of the cut groove.
Another Aspect
In another aspect of embodiment of the valve insertion method according to the present invention, a valve assembly is inserted in an already-installed line by using a milling type cutting tool, a valve assembly and an operation valve.
A worker prepares in advance the cutting tool, the valve assembly and the operation valve.
The cutting tool is supported so that it can be rotated freely around an axis set in an axial direction of the already-installed pipe, and it has cutting edges on its free end surface and outer circumferential surface.
The valve assembly has a valve casing forming a flow passage, a gate housed in the valve casing, and a valve spindle adapted to slide the gate in a direction which crosses the fluid passage at substantially right angles thereto.
The valve casing is provided with a first and second divisional cases separated from each other in the circumferential direction of the already-installed pipe.
The second divisional case is provided with a gate housing hole, and a tool entering hole.
The gate housing hole is adapted to house the gate therein when the gate is opened, and is opened in the flow passage to enable the gate to move slidingly.
The tool entering hole is opened toward the center of the already-installed pipe diagonally with respect to the gate housing hole.
The width of an opening, which is on the side of a free end of the gate, of the gate housing hole is set larger than the outer diameter of the cutting tool.
The operation valve is fixed to the valve casing so that it can open and close the tool entering hole.
This valve insertion method has an assembling step, a drilling step, a grooving step and a tool takeout step.
In the assembling step, a part of the already-installed pipe is enclosed air-tightly with the valve casing, and the gate and the cutting tool, which is independent of the gate, are housed in the valve casing with the gate and the cutting tool fixed thereto.
In the drilling step, the cutting tool is fed in the radial direction of the already-installed pipe by passing the cutting tool diagonally through a part of the gate housing hole as the cutting tool is made to take cutting motions. The xe2x80x9ccutting motionsxe2x80x9d referred to above means motions for cutting the already-installed pipe with the cutting tool rotated around the set axis mentioned above.
In the grooving step, the valve casing is turned in the circumferential direction of the already-installed pipe with the cutting motions kept being made. Owing to the turning of the valve casing in this step, the cutting tool is turned in the circumferential direction of the already-installed pipe, whereby the cutting tool is made to take feeding motions. Consequently, the already-installed pipe is cut in the whole of a circumferentially extending portion thereof with the cutting tool without producing a cut-off section. Thus, a cut groove is formed (cut) in the portion of the already-installed pipe, and extends in the direction of the range of the whole circumference thereof.
In the tool takeout step, the cutting tool is taken out from the valve casing via the operation valve after the completion of the grooving operation. Thereafter the operation valve is closed.
In the method according to the present invention, the already-installed pipe can be cut with the cutting tool rotated independently of the valve casing, so that even a cast iron pipe or a steel pipe can be cut in a short period of time.
Since the gate is housed in the valve casing in advance, an upper working tank is not required. Moreover, since the groove is cut with a small cutting tool, the dimensions of the operation valve decrease. Accordingly, the dimensions of the valve assembly as a whole decrease.
Since the gate and cutting tool are housed in the valve casing in advance, it is unnecessary to carry out an operation for replacing the cutting tool by the gate, so that the term of work decreases greatly.
The xe2x80x9calready-installed pipexe2x80x9d in the present invention means a pipe in which a fluid, such as water flows, and such a pipe is mostly buried in the ground.
The xe2x80x9cair-tightly enclosingxe2x80x9d means sealing to such an extent that does not hinder the grooving (drilling and feeding) operation and the valve insertion operation carried out thereafter. For example, a method of discharging with water the cutting chips, which are produced during the grooving operation, from a water discharge hole provided in the valve casing and opened during the grooving operation may be employed.
The xe2x80x9ccutting toolxe2x80x9d used in this valve insertion method is a milling type tool having a plurality of cutting edges in each of the free end surface and outer circumferential surface thereof, so that it does not include a bite and a cutter wheel.
In order to cut an already-installed pipe having mortar lining on an inner surface thereof, a cutting tool provided with a plurality of tips made of a hard metal, or a cutting tool having the cutting edges of diamond particles are preferably used.
The xe2x80x9ccuttingxe2x80x9d referred to in the specification of the present invention means cutting a part of a pipe wall by rotating the cutting edges. The xe2x80x9cfeed motionxe2x80x9d means causing the cutting tool to move to positions in which different parts of the pipe wall can be cut one after another with the cutting tool.
The xe2x80x9cinserting a valve assembly into an already-installed linexe2x80x9d referred to in the specification of the present invention does not mean the physical insertion of a gate into a cut-off portion of an already-installed pipe but it means setting in an already-installed line (conduit) a valve assembly for preventing the leakage of water from and regulating a flow rate in the same line.
The xe2x80x9cvalve assemblyxe2x80x9d above means an apparatus as a whole which includes a gate, a valve casing and a valve spindle.
The xe2x80x9cgatexe2x80x9d means a member for closing a flow passage. The xe2x80x9cvalve casingxe2x80x9d means a member housing the gate irrespective of the opened or closed condition of the gate.
The cutting tool used in the present invention is suitable for cutting an already-installed pipe in a non-fluid-flow-stopping condition. This cutting tool is provided with a substantially cylindrical cutter body, a plurality of first tips, a plurality of second tips, and a plurality of recesses formed in the cutter body.
The cutter body has a base end surface, a free end surface and an outer circumferential surface.
The first tips project forward from the free end surface of the cutter body.
The second tips project outward from the outer circumferential surface of the cutter body.
The recesses extend to a substantially central portion of the free end surface, and have a fan shape in a free end view of the tool body.
The cutter body has a plurality of divisional surfaces defining each of the recesses.
These divisional surfaces are arranged in the radial direction of the cylindrical body.
One of these divisional surfaces is provided thereon with not less than one first tip and not less than one second tip.
Since the cutting tool is formed in this manner, the recesses constitute discharge flow passages for discharging the cutting chips producing during the grooving operation using the first and second tips.
When an already-installed pipe is cut by rotating this cutting tool, a fluid in this pipe flows from the free end surface of the cutter body along the discharge flow passages, and is discharged from a discharge hole, whereby the cutting chips are discharged with the fluid. Accordingly, the entry of the cutting chips producing during the grooving operation into the same pipe can be restrained.